D.keys type is correct for object with numeric indexes

[Nodonisko]

D.keys type is incorrect:

const keys = D.keys({ 1: 'ahoj', 2: 'ahoj2' });
console.log(keys);

This will print [ '1', '2' ] but type for keys is readonly (1 | 2)[] which is wrong because it shouldn't be numbers but strings: readonly ('1' | '2')[]

[Nodonisko]

It's probably related to this microsoft/TypeScript#39543